The present invention relates to a laser actuated keyboard system, and, more particularly, to a laser keyboard system intended for use by persons whose disability prevents them from using conventional computer keyboards.
Various input devices have been developed to assist the disabled to control computers. Such devices include light-actuated keyboards and switches, joystick-type controllers, wand-type controllers, and various switches that respond to low-force actuation, including pneumatic actuation.
Light-actuated keyboards have typically been defined by an array of photo-responsive sensors that each correspond to a user-depressable key on a conventional computer keyboard. A light source is carried by a headmounted headband and pointed by the user toward various light-responsive surfaces to spell-out commands that are then entered into the computer. In order to facilitate the operation of the computer, software macro programs are used in conjunction with the keyboard to store a character or a character string to a particular `key`so that actuation of that key will expand the pre-programmed macro and input the pre-stored character or character string into the computer. Additionally, these light-actuated keyboards typically use replaceable templates or overlays so that different graphic indicia can be associated with each photo-responsive area of the keyboard.
More recently, laser diodes have been used as the pointable light source. While lasers provided well collimated light beams, their relatively high output has been a source of concern. While lasers provide well-collimated light beams, the intensity of consumer-grade lasers has been an eye-safety concern, especially when used by children. While the luminous flux of the laser pointer can be reduced to relatively low levels, such low levels require sensitive photo-responsive cells on the keyboard which, in turn, can lower the signal-to-noise ratio to cause spurious actuation in response to background light.